This invention relates to meter boxes and meter yokes. It more particularly relates to expansion mechanisms for mounting fluid meters in meter boxes and meter yokes.
In the past, the expansion mechanisms for liquid meters were manufactured of brass or bronze and included a cast brass or bronze body machined thereafter. These brass expansion mechanisms were mass produced at a very low cost. As a result, they were often considered expendible and the fact that they were wanting in any one of several respects was discounted due to their low cost. In situations where it was anticipated that these expansion mechanisms would fail for one reason or another, the general attitude of the art was to use them and plan to replace them when they failed.
One major shortcoming of these conventional expansion mechanism constructions was the fact that the metal was subject to being attacked or reduced by electrolytic action with resulting failure. While there are many situations where it is known that electrolytic action will or may be encountered and troublesome and oftentimes expensive efforts or steps can be made to overcome such actions, there are many other situations where it is not expected. Further, the magnitude of such action and the part or parts of the expansion mechanism construction that will be attacked by it are seldom determinable. Thus, the effective life of the expansion mechanism and meter can seldom, if ever, be determined.
Another major shortcoming of the brass expansion mechanism is that the cast portion thereof is frequently replete with holes and cavities as a result of impurities and the like in the metal. Such defects in the casting are seldom visible and frequently and unexpectedly result in ruptures, leaks and the like when the expansion mechanisms are in use.
Another shortcoming is the fact that brass and bronze have a relatively high coefficient of friction with water and certain other fluids. As a result, brass or bronze plug expansion mechanisms create a substantial resistance to fluid flow through them. These expansion mechanisms also have a number of separate parts in which cracks and crevices are defined and in which foreign matters can lodge.
Also, the arrangement used to hold the cup of the expansion mechanism to the main body was not sufficient to avoid the loss of the cup and also at the same time to prevent leaks between the main body and the cup.
Further, the main body of conventional mechanisms has a hand wheel in a star shape that makes it difficult to turn inside of a meter box in which there is limited space available between the walls of the box and the diameter of the hand wheel. Thus, frequently the person who installs the meter does not have enough clearance to turn the wheel sufficiently, and a seal is not thereby effected at the end of the fitting and leaking occurs.
In my prior designs, now recently patented, these deficiencies of the previous prior art were overcome. However, there were two additional shortcomings inherent in my prior designs.
First, there were too many parts that would be used to make up a complete working expansion mechanism. For instance, the cup and gasket were each a separate element that would bring additional costs to the manufacturing process and would require stocking of these separate elements for maintenance purposes.
Second, the seal derived from my prior expansion mechanisms required the gasket to be deformed by rotating the hand wheel until the top of gasket abutted the under surface of the annular rim. Until this contact occurred, there would be an insufficient seal that would permit leaking. Such a construction limited my prior design to full sealing contact only when the hand wheel was fully adjusted to bring about this sealing contact. Any unadjusted position therefore would be without full sealing contact.